Constant-volume regulator for turbo-compressors



P. HOFFMAN.

CONSTANT VOLUME REGULATOR EUR TURBO CMPRESSORS, APPLlcATloN FILED AuG.30. 1919.

INVENTOI? www UNITED .STATES PATENT oFFIcE.

PAUL HOFFMAN, 0F EASTON, YEITNSYLVANIA, ASSIGNCR, T0 INGERSOLL-RAND COMPANY, 0F JERSEY CITY, NEW JERSEY, A. CORPORATIG OF NEW JERSEY.

CONSTANT-VOLUME REGULATOR FOR TURBO-COMPRESSORS.

To all whom t may concern.'

Be it known that 1 PAUL HOFFMAN, a citizen of the United States, residing at Easton, in the county of Northampton and State of Pennsylvania, have invented a certain new and useful Improvement in Constent-Volume Regulators for Turbo-Compressors, 'of which vthe following is a specification.

This invention relates to turbo vcompressors, and in .particular to a regulator for a compressor of this type adapted to deliver a constant quantity offluid against varying pressures.

In installations of blast furnaces it is desired to furnish a constant volume of air when measured at atmospheric pressure and temperature, necessary to produce the metallurgical changes desired. During the operation of a blast furnace, its internal condition and, therefore its resistance to the passage of the air varies, so that it is necessary to provide some form' of regulator which will force a constant volume of y free air into the-furnace. It 'is for installations of -the above type that the regulator made in accordance -with the present invention is especially designed.

. For the above purpose advantage is taken of the variations in pressure within a Venturi tube forming the intake conduit of the turbo compressor. It is well known that with a fluid passing through a Venturi tube the difference in pressure between the full diametered portion andv the throat or Irestricted portion, varies with the square 'of the velocity and consequently varies as the square of the quantity of fluid passin through the Venturi tube. If, then, the di ference in pressure between these parts of the intake is maintained constant, we lmow 'that the velocity through the intake and consequently the quantity of airentering the compressor is constant.

An object of the present invention is, therefore, to provide a regulator utilizing this action of a Venturi tube to vary the motive fluid supplied to the motor drivingI the turbo compressor so as to maintain' a constant quantity of fluid-usually airpassing through the compreor supplying the blast furnaces or other installations reuiring aconstant quantity oflair against ilerent pressures' above or below normal.l

Specification of Letters Patent.

' hereto and A further object of the invention is tov provide` a governor sensitive enough to react upon very slight variation of the veloc- 1 ity-head at the lVenturi throat and to bring about such change inthe speed of the com-- struction and operation set forth in the following specification:

In the figure of the drawing annexed ormlng a part of the specification, a cross sectional view of a complete regulator is shown adapted to operate as above described.

It is a characteristic of turbo-compressors that if maintained at a constant s eed the volume will vary inversely with t e pressure, so that when the pressure ainst wh1ch the turbo-compressor is operatmg is increased the amount of iluid compressed is diminished, and vice versa. If then a constant quantity of'uid is to be compressed against different or variable pressures the governor or regulator must act to increase the speed of the compressor to maintain the same quantity going through the compressor against the increased ressure. Similarly, when the pressure against which the compressor is o erating is lowered the speed must be re uced to prevent an increased quantity of iiuid being compressed.

Referring now more particularly to the drawing, the intake of a turbo-com ressor is shown at 1, which is formed as a enturi tube having a full diametered portion 2v at which the air or other iuid enters and a throat 3 at which the velocity of the incoming fluid is greatest. As is well known, the static pressure of the fluid at the throat 3 is less than that at the full diametered portions of the venturi, the difference in the pressure at the throat from that at the full diametered portions varying with the square of thevelocity and consequentlyv with the square of the quantity passing through the venturi.

At 4 is shown the main uid supply conduit for admitting motive Huid 'to operate the motor for the com ressor, and at 5 is Patented J une 28, 1921. Application led August 30, 1,919. Serial No. 320,91L`

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shown a throttle valve 1n this conduit 4 for f varying the amount of motive fluid su plied to ,the` motor to maintain a constant ow of air being compressed throughY the compressor at varyingpressures dependent upon the condition of the blast furnace or other apparatus beingsupplied with a constant volume of air or other gas. Tov operate the valve 5 a bellshaped iioat 6 is provided suitably mounted to slide vertically within a receptacle 7 having a certain amount of water or other suitable liquid to seal the lower end of this bellshaped ioat. A pipe or other conduit 8 extends up within the receptacle 7 and within the bell shaped float 6 to av above the water level is a conduit 10 suitably connected with the full diameter portion 2 of the Venturi intake of the compressor so that a difference in pressure will 'be produced in the conduits 9 and 10 when fluid is passing through the intake of the compressor, but differences in pressure Within conduits 9 and 104 will produce pressure diferences between inside and outside of iioat 6 and thus tend to unbalance the position of this float 6.

Attached to the top surface of the bell sha ed ioat 6 is a stem 11 to which is attac ed a bell crank lever 12, the opposite end of the lever 12 having anadjustable spring 13 to balancethe pressure difference between the inside and outside of the float 6, and also its weight. The connection between the bell shaped. float 6 and the lever 12 includes a water seal comprising an annular extension 14 to the top casing 15 and,

surrounding the stem 11, an annular body 16 and also a pipe 17 made fast into the top casing 15. ithin the spaces between these parts water or other suitable liquid is placed. It will thus be seen that movement of the oat 6 will be without material friction other than that produced by the viscosity of the water seals.

The pressure diference necessary to maintain the oat 6 at a given position is depend- -ent upon the tension of spring 13, which pressure difference as above indicated, will va with differences in velocity of Huid through the Venturi intake. In connection with the .lever 124 is a series of levers or linkages 18and 19 through which the move- `mentof the float 6 operates a pilot valve 19a and through this pilot valve operates a piston 2O directly connected with the valve 5. The first eiect of a movement of the `linkage system 18 and 19 is therefore to below lthe piston 20, thus causing the piston 20, and consequently, the valve 5, to vary its position.

The position of the pilot valve 19 is adjustable and the whole relation in the va- 'rious elements from ioat 6 to valve 5 is such that, for a given amount of Huid iowing through the venturi and a given tension of the spring 13, a certain amount of motive iiuid is passed through valve 5 which will maintain the speed of the compressor constant. Any change in the volume of fluid passing through the venturi will result, through disturbance of the equilibrium existing in the regulator, in a change of the valve 5, consequently varying the speed of the motor until the former balance is reestablished and thevolume through the venturi brought back to its original value.

Associated with the linkage members 18 and 19 is a suitable centrifugal governor shaft 21 which, operating through a bell crank lever 22 and distance piece 23 is attached at one extremity of the link 18. This speed governor shaft 21 is intended to remain fixed in its position until a given safe speed of the motor and compressor is exceeded, at which speed shat 21- moves slightly to the left, thus raising oneend of the link 18 and, through the link 19, closes the valve 5. This prevents a safe speed of the motor` and compressor being exceeded but' has no effect upon the regulation of the motor within the operable and safe speeds and within normal capacities of the compressor.

At the opposite end of the link 18 is dash pot 24 designedto prevent violent iuctustions in the movement of the float 6 and thus of the valve 5 with resulting irregular hunting operation of the compressor. The dash pot 24 fits closely within its cylinder 25, but its resistance may be regulated by a bypass.

Briefly, the operation of the above regulator is as follows: In starting, with oil or other medium under pressure supplied through port 28 to below the piston 20, the valve 5 is held in open position and this position of the valve 5 ismaintained vuntil a velocity of Huid is attained in the intake 1 of the compressor corresponding to ya con- ,.stant volume of free air being suppliedper minute. This velocity produces a definite 'diierence in pressure between thel throat 3 and the full diameter portion 2 of the intake and consequently' a constant difference in elevation. of the parts oi the water seal inside and outside of the bell shaped float 6 which has the e'ect of unbalancing the ioat 6.v The spring 13 is desi ed to counterbalance thisy condition pro uced byl the weight of the oat 6 so that variations in the tension of the spring 13 rovide means for varying the volume of alr admitted to the compressor for the reason that with a greater tension of spring 13 a greater difference in pressure must exist in the parts of the venturi and consequently the velocity through the venturi must be greater to overcome this increased spring tension. As soon as this definite pressure difference in the float 6 has been attained the float 6 is forced downwardly, without friction, thus varying the position of the linkage 18 and 19 and through the changing position of the pilot valve 19 the fluid pressure is cut oil' from 'below the piston 20 and admitted to the portion above this piston, thus Aforcing the valve 5 toward closed position. Movement of the valve toward its closed position, however, has the effect of cuttin on the supplying of Huid above the plston 20 therefore stopping the closing movement o the valve 5 until the linkage 18-19 has again moved din accordance with a further movement of the oat 6. This continued movement of the' float, the pilot valve and the throttle valve 5 is maintained until a point is reached at which the linkage 18 and 19 and float 6 are balanced. To increase the amount of fluid being compressed it is only necessary to increase the tension of spring 13 which will require a greater difference in pressure between the parts of the intake and consequently a higher velocity of the fluid entering the compressor.

During the operation of the compressor as soon as the resistance of the furnace or other apparatus being supplied is decreased the first eiect is to increase the velocity of the compressor which will have the ell'ect of increasing the fluid velociy through the intake of the compressor an consequently increasing the pressure difference holding the lioat 6, and thus forcing the oat to move downwardly thus varying the position of the links 18-19 which through the operation of they pilot valve 19a will force the valve 5 slowly into a new position decreasing the amount of Huid admitted to the compresser motor.

Similarly when the pressure against which the compressor is operating increases the osition of the float 6 is raised and the va ve 5 moves to a position to admit more fluid to the motor to increase its speed.

Having thus described my invention what ll claim is:

1. A constant volume regulator for a motor driven turbo compressor, comprising a Venturi tube forming the intake of the compressor, a float, movement of which is adapted to vary the amount of power to drive the motor of said turbo compressor, said float being forced up or down by iiuctuations in pressure differences between the throat and full diametered portions of said Venturi intake tube, whereby a substantially constant quantity of uid is delivered to the intake of the turbo compressor regard-'.-

Vsaid two points in the intake will cause the float to move up or down to vary the amount of iiuid supplied to the motor of said turbo compressor.

3. In a motor driven compressor, the combination of an intakeconduit having a restricted portion, a bell shaped float movable up and down by variations in the difference in pressure above and below said float, and means connecting'the space below said oat to the restricted portion of said intake conduit, the space above said Heat being connected to a full diametered portion of lsaid intake conduit. 4f. In a motor driven turbo compressor, the combination of an intake conduit having a portion adapted to increase the velocity of the incoming iiuid, a water sealed receptacle, a bell shaped lioat within said receptacle, means connecting the space within said oat to a point in the intake conduit in which the velocity of the fluid is increased and means connecting the portion of the receptacle above the ioat with a portion of the intake conduit in which the velocity of the fluid is normal.

5. A regulator for a motor driven compressor, comprising a water sealed bell shaped oat, movement of .which varies the power supplied to the motor to drive the compressor, an intake conduit for the compressor and means to vary the position of said oat comprising conduits connecting the top and bottom of the float with different points in the intake of said compressor at which the pressure is different due to the velocity in the intake.

6. A. regulator for a motor driven compressor, comprising a water sealed bell shaped float, movement of which varies the power supplied to the motor to drive the compressor, an intake conduit for the compressor, means to vary the positionof said float comprising pressure conduits connecting the top and bottom of the float with different points in the intake of said compressor in which the static pressures are different due to the velocity in the intake.

7. A regulator for a motory driven compressor, comprising a water sealed bell power supplied to the motor to drive the i compressor, an intake conduit for the compressor and differential meansto vary the position of the said oat comprising pressure conduits connecting the top and bottom ofthe oat with diierent points in'the intake of said compressor having different pressures due to the velocity in the intake.

8. A regulator or a motor drivenfcompresser, a throttle valve for the motor, said regulator comprising a water sealed bell shaped float, movement of which varies the power supplied to the motor to drive the compressor, an intake conduit for the compressor conduit means connected to different points in spaced relation in the intake of said compressor at which the pressures are different d ue to the velocity in said intake to i move said ioat, and linkage connecting the ioat with the said throttle valve, means for resisting the movement of the float and means for regulating said resistance where- .by a constant volume of fluid may be compressed. y

' 9. A constant volume regulator for a motor driven turbo-compressor, comprising an intake for said turbo-compressor in the between the pressure on the said two sides of the ioat will cause the iioat to move up or down to vary the amount of fluid supplied to the motor of saidturbo-compressor.

y 10. YA constant volume regulator for a ,motor driven turbo-compressor, comprising an intake J'or said turbo-compressor 1n the form of a Venturi tube, a water sealed receptacle, a bell shaped float inclosed within said receptacle, and movable u and down by variations in the diiierence m pressure above and below said lioat, the space below the oat being connected to the throat of said Venturi tube and subject to the variations in fluid pressure at said throat.

In testimony whereof I have hereunto set m hand.

y PAUL HOFFMAN. 

